[Leo.G (Leo)]

I want to check the collimation of my old Skywatcher 152 Achro. I've removed the lens cell several times to clean it in the past and think it probably wouldn't be a bad idea to check it. The lens cell was marked before removal (cheap nail polish is great for the purpose) and always put back in it's original screw holes.
There are 3 adjustment grub screws on the cell.



I have a green laser and I'm intending to machine an adapter on the lathe to fit into a 2" imaging adapter I had made so I can point it directly at the lens from the rear of the 1200mm scope but how would I know if it was out of alignment?
I'll be putting the laser in the chuck of the lathe to check for alignment of it before I do anything.

Is it as simple as if the laser dot/beam is centred the scope is fine because with 3 adjustment screws on the lens cell I'm thinking it could still be central but the lens cell not square.
Does the laser deviate at an angle if the lens is not square?
I know, that's mirrors but I DO NOT have a clue.

Now I think I like reflectors despite always being fond of refractors.
Collimation is easy on my 8" Newt.